Alpine climate

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(Redirected from
Mountain climate
)
For the climate of the mountains named the "Alps", see Climate of the Alps.
above sea level in California

Alpine climate is the typical climate for elevations above the tree line, where trees fail to grow due to cold. This climate is also referred to as a mountain climate or highland climate.

Definition

There are multiple definitions of alpine climate.

In the Köppen climate classification, the alpine and mountain climates are part of group E, along with the polar climate, where no month has a mean temperature higher than 10 °C (50 °F).[1]

According to the

Holdridge life zone
system, there are two mountain climates which prevent tree growth :

a) the alpine climate, which occurs when the mean

biotemperature of a location is between 1.5 and 3 °C (34.7 and 37.4 °F). The alpine climate in Holdridge system is roughly equivalent to the warmest tundra
climates (ET) in the Köppen system.

b) the alvar climate, the coldest mountain climate since the biotemperature is between 0 °C and 1.5 °C (biotemperature can never be below 0 °C). It corresponds more or less to the coldest tundra climates and to the ice cap climates (EF) as well.

Holdrige reasoned that plants net primary productivity ceases with plants becoming dormant at temperatures below 0 °C (32 °F) and above 30 °C (86 °F).[2] Therefore, he defined biotemperature as the mean of all temperatures but with all temperatures below freezing and above 30 °C adjusted to 0 °C; that is, the sum of temperatures not adjusted is divided by the number of all temperatures (including both adjusted and non-adjusted ones).

The variability of the alpine climate throughout the year depends on the latitude of the location. For tropical oceanic locations, such as the summit of

Mount Washington in New Hampshire, the temperature varies seasonally, but never gets very warm.[4][5]

Cause

The temperature profile of the atmosphere is a result of an interaction between radiation and convection. Sunlight in the visible spectrum hits the ground and heats it. The ground then heats the air at the surface. If radiation were the only way to transfer heat from the ground to space, the greenhouse effect of gases in the atmosphere would keep the ground at roughly 333 K (60 °C; 140 °F), and the temperature would decay exponentially with height.[6]

However, when air is hot, it tends to expand, which lowers its density. Thus, hot air tends to rise and transfer heat upward. This is the process of

adiabatic lapse rate, which is approximately 9.8 °C per kilometer (or 5.4 °F per 1000 feet) of altitude.[6]

The presence of water in the atmosphere complicates the process of convection. Water vapor contains latent

precipitation becomes snow and the winds increase. The temperature continues to drop until the tropopause, at 11,000 metres (36,000 ft), where it does not decrease further. This is higher than the highest summit
.

Distribution

Although this climate classification only covers a small portion of the Earth's surface, alpine climates are widely distributed. They are present in the

Pacific
.

The lowest altitude of alpine climate varies dramatically by latitude. If alpine climate is defined by the tree line, then it occurs as low as 650 metres (2,130 ft) at 68°N in Sweden,[14] while on Mount Kilimanjaro in Tanzania, the tree line is at 3,950 metres (12,960 ft).[14]

See also

References

  1. ISBN 978-0-13-020263-5
    .
  2. S2CID 11733879
    . Retrieved 27 May 2015.
  3. ^ "Period of Record Monthly Climate Summary". MAUNA LOA SLOPE OBS, HAWAII. NOAA. Retrieved 2012-06-05.
  4. ^ "Station Name: NH MT WASHINGTON". National Oceanic and Atmospheric Administration. Retrieved 9 June 2014.
  5. ^ "WMO Climate Normals for MOUNT WASHINGTON, NH 1961–1990". National Oceanic and Atmospheric Administration. Retrieved 9 June 2014.
  6. ^ a b Goody, Richard M.; Walker, James C.G. (1972). "Atmospheric Temperatures" (PDF). Atmospheres. Prentice-Hall. Archived from the original (PDF) on 2016-07-29. Retrieved 2016-05-02.
  7. ^ "Dry Adiabatic Lapse Rate". tpub.com. Archived from the original on 2016-06-03. Retrieved 2016-05-02.
  8. ISBN 978-0-9678550-9-7
    .
  9. ^ Dommasch, Daniel O. (1961). Airplane Aerodynamics (3rd ed.). Pitman Publishing Co. p. 22.
  10. ^ "Mountain Environments" (PDF). United Nations Environment Programme World Conservation Monitoring Centre. Archived from the original (PDF) on 2011-08-25.
  11. ^ "Factors affecting climate". The United Kingdom Environmental Change Network. Archived from the original on 2011-07-16.
  12. ISBN 9780816072293
    .
  13. AEMET
    . Retrieved 17 June 2021.
  14. ^
    S2CID 8647814. Archived from the original
    (PDF) on 2006-09-11. Retrieved 2015-08-05.
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